/**
 * Autocorrelation-based pitch detection
 * Fast, reliable fallback algorithm for monophonic pitch detection
 */
/**
 * Autocorrelation configuration
 */
export interface AutocorrelationConfig {
    sampleRate?: number;
    minFrequency?: number;
    maxFrequency?: number;
    windowType?: 'hann' | 'hamming' | 'blackman' | 'rectangular';
    threshold?: number;
    usePreEmphasis?: boolean;
    preEmphasisCoeff?: number;
    useCenterClipping?: boolean;
    centerClippingThreshold?: number;
}
/**
 * Autocorrelation result
 */
export interface AutocorrelationResult {
    frequency: number;
    confidence: number;
    lag: number;
    autocorrelation: Float32Array;
    peaks: number[];
}
/**
 * Autocorrelation pitch detector
 */
export declare class AutocorrelationDetector {
    private config;
    private window;
    constructor(config?: AutocorrelationConfig);
    /**
     * Detect pitch using autocorrelation
     */
    detectPitch(signal: Float32Array): AutocorrelationResult | null;
    /**
     * Preprocess signal for better autocorrelation
     */
    private preprocessSignal;
    /**
     * Apply pre-emphasis filter
     */
    private applyPreEmphasis;
    /**
     * Apply center clipping
     */
    private applyCenterClipping;
    /**
     * Compute autocorrelation function
     */
    private computeAutocorrelation;
    /**
     * Find peaks in autocorrelation
     */
    private findPeaks;
    /**
     * Check if index is a local maximum
     */
    private isLocalMaximum;
    /**
     * Select best peak from candidates
     */
    private selectBestPeak;
    /**
     * Correct octave errors by checking harmonic relationships
     */
    private correctOctaveErrors;
    /**
     * Detect pitch with sub-sample accuracy using parabolic interpolation
     */
    detectPitchInterpolated(signal: Float32Array): AutocorrelationResult | null;
    /**
     * Batch pitch detection
     */
    detectPitchBatch(signals: Float32Array[]): (AutocorrelationResult | null)[];
    /**
     * Update configuration
     */
    updateConfig(config: Partial<AutocorrelationConfig>): void;
    /**
     * Get current configuration
     */
    getConfig(): Readonly<Required<AutocorrelationConfig>>;
}
/**
 * Quick utility: Detect pitch using autocorrelation
 */
export declare function detectPitchAutocorrelation(signal: Float32Array, sampleRate?: number, options?: AutocorrelationConfig): number | null;
/**
 * Autocorrelation utilities
 */
export declare const AutocorrelationUtils: {
    /**
     * Calculate pitch confidence from autocorrelation strength
     */
    calculateConfidence(strength: number, threshold?: number): number;
    /**
     * Check if autocorrelation result is reliable
     */
    isReliable(result: AutocorrelationResult, minConfidence?: number): boolean;
    /**
     * Convert lag to frequency
     */
    lagToFrequency(lag: number, sampleRate: number): number;
    /**
     * Convert frequency to lag
     */
    frequencyToLag(frequency: number, sampleRate: number): number;
    /**
     * Find fundamental frequency from harmonic series
     */
    findFundamentalFromHarmonics(peaks: number[], sampleRate: number): number | null;
};